- Add IOllamaTool and IOllamaToolCall types for native function calling
- Add think parameter to IOllamaModelOptions for reasoning models (GPT-OSS, QwQ)
- Add tools parameter to IOllamaChatOptions
- Add toolCalls to response interfaces (IOllamaStreamChunk, IOllamaChatResponse)
- Update chat(), chatStreamResponse(), collectStreamResponse(), chatWithOptions() to support native tools
- Parse tool_calls from Ollama API responses
- Add support for tool message role in conversation history